linux-ext4 - Re: [PATCH 3/3] f2fs: fix inode rwsem regression

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Date:   Thu, 12 Sep 2019 14:17:32 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Goldwyn Rodrigues <rgoldwyn@...e.de>,
        <linux-fsdevel@...r.kernel.org>
CC:     <linux-ext4@...r.kernel.org>, <linux-btrfs@...r.kernel.org>,
        <hch@...radead.org>, <andres@...razel.de>, <david@...morbit.com>,
        <riteshh@...ux.ibm.com>, <linux-f2fs-devel@...ts.sourceforge.net>,
        "Goldwyn Rodrigues" <rgoldwyn@...e.com>
Subject: Re: [PATCH 3/3] f2fs: fix inode rwsem regression

On 2019/9/12 0:45, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@...e.com>
> 
> This is similar to 942491c9e6d6 ("xfs: fix AIM7 regression")
> Apparently our current rwsem code doesn't like doing the trylock, then
> lock for real scheme.  So change our read/write methods to just do the
> trylock for the RWF_NOWAIT case.
> 
> We don't need a check for IOCB_NOWAIT and !direct-IO because it
> is checked in generic_write_checks().
> 
> Fixes: b91050a80cec ("f2fs: add nowait aio support")
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@...e.com>
> ---
>  fs/f2fs/file.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 3e58a6f697dd..c6f3ef815c05 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3134,16 +3134,12 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  		goto out;
>  	}
>  
> -	if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT)) {
> -		ret = -EINVAL;
> -		goto out;
> -	}

We have removed above redundant check, could you rebase to dev-test branch of
Jaegeuk's git tree?

Otherwise it looks good to me.

Thanks,

> -
> -	if (!inode_trylock(inode)) {
> -		if (iocb->ki_flags & IOCB_NOWAIT) {
> +	if (iocb->ki_flags & IOCB_NOWAIT) {
> +		if (!inode_trylock(inode)) {
>  			ret = -EAGAIN;
>  			goto out;
>  		}
> +	} else {
>  		inode_lock(inode);
>  	}
>  
>